The relative paralysis of our arteries for hours after eating fast food and cheesecake may also occur after consuming olive oil. Olive oil was found to have the same impairment to endothelial function as high-fat foods like sausage and egg breakfast sandwiches. (See my Olive Oil and Artery Functionvideo for an illustrative chart with different foods.)

Studies that have suggested endothelial benefits after olive oil consumption have measured something different: ischemia-induced dilation as opposed to flow-mediated dilation. There's just not good evidence that's actually an accurate index of endothelial function, which is what predicts heart disease. Hundreds of studies have shown that the ischemia-induced dilation test can give a false negative result.

Other oils have also been shown to have deleterious results on endothelial function. A significant and constant decrease in endothelial function appears within three hours after each meal, independent of the type of oil and whether the oil was fresh or deep fried. Olive oil may be better than omega-6-rich oils or saturated fats, but it still showed adverse effects. This was the case with regular, refined olive oil. But what about extra-virgin olive oil?

Extra-virgin olive oil retains a fraction of the anti-inflammatory phytonutrients found in the olive fruit, and so doesn't appear to induce the spike in inflammatory markers caused by regular olive oil. What does that mean for our arteries? Extra-virgin olive oil may have more of a neutral effect compared to butter, which exerted a noxious effect that lasted for up to six hours--basically right up until our next meal. In the largest prospective study ever to assess the relationship between olive oil consumption and cardiac events like heart attacks, there was a suggestion that virgin olive oil may be better than regular olive oil, but neither was found to significantly reduce heart attack rates after controlling for healthy dietary behaviors like vegetable intake, which tends to go hand-in-hand with olive oil intake.

There have also been studies showing that even extra-virgin olive oil, contrary to expectations, may significantly impair endothelial function. Why then do some studies suggest endothelial function improves on a Mediterranean diet, which is rich in olive oil? It may be because the Mediterranean diet is also rich in whole grains, fruits, vegetables, beans, and walnuts. Fruits and vegetables appear to provide some protection against the direct impairment of endothelial function produced by high-fat foods, including olive oil; therefore, improvements in health may be in spite of, rather than because of, the oil. In terms of their effects on post-meal endothelial function, the beneficial components of the Mediterranean diet may primarily be the antioxidant-rich foods, the vegetables, fruits, and their derivatives, such as balsamic vinegar. Adding some vegetables to a fatty meal may partially restore arterial functioning and blood flow.

The relative paralysis of our arteries for hours after eating fast food and cheesecake may also occur after consuming olive oil. Olive oil was found to have the same impairment to endothelial function as high-fat foods like sausage and egg breakfast sandwiches. (See my Olive Oil and Artery Functionvideo for an illustrative chart with different foods.)

Studies that have suggested endothelial benefits after olive oil consumption have measured something different: ischemia-induced dilation as opposed to flow-mediated dilation. There's just not good evidence that's actually an accurate index of endothelial function, which is what predicts heart disease. Hundreds of studies have shown that the ischemia-induced dilation test can give a false negative result.

Other oils have also been shown to have deleterious results on endothelial function. A significant and constant decrease in endothelial function appears within three hours after each meal, independent of the type of oil and whether the oil was fresh or deep fried. Olive oil may be better than omega-6-rich oils or saturated fats, but it still showed adverse effects. This was the case with regular, refined olive oil. But what about extra-virgin olive oil?

Extra-virgin olive oil retains a fraction of the anti-inflammatory phytonutrients found in the olive fruit, and so doesn't appear to induce the spike in inflammatory markers caused by regular olive oil. What does that mean for our arteries? Extra-virgin olive oil may have more of a neutral effect compared to butter, which exerted a noxious effect that lasted for up to six hours--basically right up until our next meal. In the largest prospective study ever to assess the relationship between olive oil consumption and cardiac events like heart attacks, there was a suggestion that virgin olive oil may be better than regular olive oil, but neither was found to significantly reduce heart attack rates after controlling for healthy dietary behaviors like vegetable intake, which tends to go hand-in-hand with olive oil intake.

There have also been studies showing that even extra-virgin olive oil, contrary to expectations, may significantly impair endothelial function. Why then do some studies suggest endothelial function improves on a Mediterranean diet, which is rich in olive oil? It may be because the Mediterranean diet is also rich in whole grains, fruits, vegetables, beans, and walnuts. Fruits and vegetables appear to provide some protection against the direct impairment of endothelial function produced by high-fat foods, including olive oil; therefore, improvements in health may be in spite of, rather than because of, the oil. In terms of their effects on post-meal endothelial function, the beneficial components of the Mediterranean diet may primarily be the antioxidant-rich foods, the vegetables, fruits, and their derivatives, such as balsamic vinegar. Adding some vegetables to a fatty meal may partially restore arterial functioning and blood flow.

The phenomenon of postprandial angina was described more than 200 years ago: chest pain that occurs after a meal, even if you're just sitting down and resting. This could be intuitively attributed to redistribution of blood flow away from the heart to the gut during digestion. However, such a mechanism could not be demonstrated experimentally.

The problem appears to be within the coronary arteries themselves. The clue came in 1955 when researchers found they could induce angina in people with heart disease just by having them drink fat. My video Fatty Meals May Impair Artery Function includes a fascinating graph of so-called lactescence, or milkiness, over time. It shows how their blood became increasingly milky with fat over the next five hours, and each of the ten attacks of angina was found to occur about four-and-a-half to five hours after the fatty meal, right when blood milkiness was at or near its peak. After a nonfat meal with the same bulk and calories, but made out of starch, sugar, and protein, no anginal pain was elicited in any of the patients.

To understand how the mere presence of fat in the blood can affect blood flow to the heart, we need to understand the endothelium, the inner lining of all of our blood vessels. Our arteries are not just rigid pipes; they are living, breathing organs that actively dilate or constrict, thinning or thickening the blood and releasing hormones, depending on what's needed. This is all controlled by the single inner layer, the endothelium, which makes it the body's largest endocrine (hormone-secreting) organ. When it's all gathered up, the endothelium weighs a total of three pounds and has a combined surface area of 700 square yards.

We used to think the endothelium was just an inert layer lining our vascular tree, but now we know better:

Researchers found that low-fat meals tend to improve endothelial function, whereas high-fat meals tend to worsen it. This goes for animal fat, as well as isolated plant fats, such as sunflower oil. But, maybe it's just the digestion of fat rather than the fat itself? Our body can detect the presence of fat in the digestive tract and release a special group of hormones and enzymes. Researchers tried feeding people fake fat and found that the real fat deprived the heart of blood while the fake fat didn't. Is our body really smart enough to tell the difference?

A follow-up study settled the issue. Researchers tried infusing fat directly into people's bloodstream through an IV to sneak it past your mouth and brain. Within hours, their arteries stiffened, significantly crippling their ability to relax and dilate normally. So it was the fat after all! This decrease in the ability to vasodilate coronary arteries after a fatty meal, just when you need it, could explain the phenomenon of after-meal angina in patients with known coronary artery disease.

The phenomenon of postprandial angina was described more than 200 years ago: chest pain that occurs after a meal, even if you're just sitting down and resting. This could be intuitively attributed to redistribution of blood flow away from the heart to the gut during digestion. However, such a mechanism could not be demonstrated experimentally.

The problem appears to be within the coronary arteries themselves. The clue came in 1955 when researchers found they could induce angina in people with heart disease just by having them drink fat. My video Fatty Meals May Impair Artery Function includes a fascinating graph of so-called lactescence, or milkiness, over time. It shows how their blood became increasingly milky with fat over the next five hours, and each of the ten attacks of angina was found to occur about four-and-a-half to five hours after the fatty meal, right when blood milkiness was at or near its peak. After a nonfat meal with the same bulk and calories, but made out of starch, sugar, and protein, no anginal pain was elicited in any of the patients.

To understand how the mere presence of fat in the blood can affect blood flow to the heart, we need to understand the endothelium, the inner lining of all of our blood vessels. Our arteries are not just rigid pipes; they are living, breathing organs that actively dilate or constrict, thinning or thickening the blood and releasing hormones, depending on what's needed. This is all controlled by the single inner layer, the endothelium, which makes it the body's largest endocrine (hormone-secreting) organ. When it's all gathered up, the endothelium weighs a total of three pounds and has a combined surface area of 700 square yards.

We used to think the endothelium was just an inert layer lining our vascular tree, but now we know better:

Researchers found that low-fat meals tend to improve endothelial function, whereas high-fat meals tend to worsen it. This goes for animal fat, as well as isolated plant fats, such as sunflower oil. But, maybe it's just the digestion of fat rather than the fat itself? Our body can detect the presence of fat in the digestive tract and release a special group of hormones and enzymes. Researchers tried feeding people fake fat and found that the real fat deprived the heart of blood while the fake fat didn't. Is our body really smart enough to tell the difference?

A follow-up study settled the issue. Researchers tried infusing fat directly into people's bloodstream through an IV to sneak it past your mouth and brain. Within hours, their arteries stiffened, significantly crippling their ability to relax and dilate normally. So it was the fat after all! This decrease in the ability to vasodilate coronary arteries after a fatty meal, just when you need it, could explain the phenomenon of after-meal angina in patients with known coronary artery disease.